/*
 * Licensed to the Apache Software Foundation (ASF) under one or more
 * contributor license agreements.  See the NOTICE file distributed with
 * this work for additional information regarding copyright ownership.
 * The ASF licenses this file to You under the Apache License, Version 2.0
 * (the "License"); you may not use this file except in compliance with
 * the License.  You may obtain a copy of the License at
 *
 *      http://www.apache.org/licenses/LICENSE-2.0
 *
 * Unless required by applicable law or agreed to in writing, software
 * distributed under the License is distributed on an "AS IS" BASIS,
 * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
 * See the License for the specific language governing permissions and
 * limitations under the License.
 */
package org.gss_project.gss.server.rest;

import java.io.ByteArrayOutputStream;
import java.io.IOException;
import java.io.OutputStreamWriter;
import java.util.BitSet;

/**
 *
 * This class is very similar to the java.net.URLEncoder class.
 *
 * Unfortunately, with java.net.URLEncoder there is no way to specify to the
 * java.net.URLEncoder which characters should NOT be encoded.
 *
 * This code was moved from DefaultServlet.java
 *
 * @author Craig R. McClanahan
 * @author Remy Maucherat
 */
public class URLEncoder {
	/**
	 *
	 */
	protected static final char[] hexadecimal =
	{'0', '1', '2', '3', '4', '5', '6', '7', '8', '9',
		'A', 'B', 'C', 'D', 'E', 'F'};

	/**
	 * Array containing the safe characters set.
	 */
	protected BitSet safeCharacters = new BitSet(256);

	/**
	 *
	 */
	public URLEncoder() {
		for (char i = 'a'; i <= 'z'; i++)
			addSafeCharacter(i);
		for (char i = 'A'; i <= 'Z'; i++)
			addSafeCharacter(i);
		for (char i = '0'; i <= '9'; i++)
			addSafeCharacter(i);
	}

	/**
	 * @param c
	 */
	public void addSafeCharacter( char c ) {
		safeCharacters.set( c );
	}

	/**
	 * @param path
	 * @return the encoded string
	 */
	public String encode( String path ) {
		int maxBytesPerChar = 10;
		StringBuffer rewrittenPath = new StringBuffer(path.length());
		ByteArrayOutputStream buf = new ByteArrayOutputStream(maxBytesPerChar);
		OutputStreamWriter writer = null;
		try {
			writer = new OutputStreamWriter(buf, "UTF8");
		} catch (Exception e) {
			e.printStackTrace();
			writer = new OutputStreamWriter(buf);
		}

		for (int i = 0; i < path.length(); i++) {
			int c = path.charAt(i);
			if (safeCharacters.get(c))
				rewrittenPath.append((char)c);
			else {
				// convert to external encoding before hex conversion
				try {
					writer.write((char)c);
					writer.flush();
				} catch(IOException e) {
					buf.reset();
					continue;
				}
				byte[] ba = buf.toByteArray();
				for (int j = 0; j < ba.length; j++) {
					// Converting each byte in the buffer
					byte toEncode = ba[j];
					rewrittenPath.append('%');
					int low = toEncode & 0x0f;
					int high = (toEncode & 0xf0) >> 4;
				rewrittenPath.append(hexadecimal[high]);
				rewrittenPath.append(hexadecimal[low]);
				}
				buf.reset();
			}
		}
		return rewrittenPath.toString();
	}
}
